[TenTec] Johnson matchbox tuner

[Randy Russe3ll]

I was always confused about the third cap.  Are you
shunting it across the third tap to use with ur TEN
TEC STATIO?  Or  do you run two gangs (one for each
side)of a differential Cap in series with each side of
the parrelell lines.  I understand 160M will load
fine.  The other config Cebil proposes is to FLOAT the
output cap from ground.  Instead of grounding one
side, of both gangs, to ground, the (2)gnd sides are
wired to to the parrelel feedline. Which gives you in
effect, both bal. lines running in series through
those caps.  There is absolutely no reason that a
Matchbox can't handle 30M without a bunch of Mods.  My
guess is if yout TEN TEC station is having trouble
matching 30M, Your antenna resistance is to low or at
re 50 ohm resonance or lower. Try just adding a foot
to the end of you 30m antenna and that should knock
the resistance up a few hundred ohms. Just raising and
lowering ur antenna will take a 50 ohm feedpoint
through a 2:1 swr range, but who wants to lower their
antenna to adjust swr.  I put up an 80 M dipole fed
with bal line and the only spot that gave me trouble
was 80m, the spot it was cut for. On 40 M, now a full
wave dipole and fed at the usual "no-no" spot near the
current null, loaded up like "swiiiiing" My best swr .
 When I adjusted the dipole length from 136 or so feet
to 140 ft.  Everything hit for low swr.  Just add 2-5%
to your antenna length, which would put a coax antenna
out of the ballpark, but puts the Bal tuner into it's
sweet spot.  Last thing adjust feedline by 1/8 or 1/16
wavelength (of ur problem freq.)at a time until you
get closer to a voltage node, that will get you in the
sweet spot if nothing else worked. 

--- NJ0IP <Rick at DJ0IP.de> wrote:

> Lyle, 
> 
> I suggest adding a third variable capacitor (like in
> the Annecke boxes).
> You can see this on L.B. Cybek (W4RNL) web site. 
> Look for his article on
> "Link Coupling" or "Link Coupled Matchboxes".
> 
> I will also send you the details (off reflector) in
> a PDF file.
> 
> In general, if you can't prune your antenna and
> feedline lengths to find a
> match as is, then determine which position (40m or
> 20m) gives you the best
> SWR on 30m. Then try adjusting the coil taps for
> that band.  Try just a wee
> bit more or less inductance and keep it symmetrical.
>  You should be able to
> find a tap which enables 30m to work along with
> either the modified 20m or
> 40m taps.  The 3rd variable capacitor is the icing
> on the cake and enable
> getting the SWR even lower on all bands.
> 
> BEFORE YOU TOUCH ANYTHING, don't forget to write
> down the exact settings of
> the coil taps before the modification.
> 
> Good luck.
> 
> 73
> Rick
> 
> 
> 
> 
> -----Original Message-----
> From: tentec-bounces at contesting.com
> [mailto:tentec-bounces at contesting.com]
> On Behalf Of Lyle Dunlap
> Sent: Monday, March 27, 2006 5:25 AM
> To: tentec at contesting.com
> Subject: [TenTec] Johnson matchbox tuner
> 
> Someone came out with a fix for using a Johnson
> Match Box on 30M,  here on
> the reflector.  Would that person or someone who
> remebers tell me how it was
> done?  Friend wants info.  (forgive me for non TT
> subj matter)
> 
> Lyle W9FCX
> 
> 
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